void main() {
  // 准备购物车数据
  List carts = [
    {"count": 2, "price": 10.0, "selected": true},
    {"count": 1, "price": 30.0, "selected": false},
    {"count": 5, "price": 20.0, "selected": true},
  ];

  double totalPrice = 0;

  for (var goods in carts) {
    if(goods['selected']){
      totalPrice += goods['price'] * goods['count'];
    }
  }
  print('购物车的总价为：${totalPrice}');
}
